"AES" wrote
>I have a number of symbolic results which emerge from a Mathematica
>calculation in the form
>
> a Exp[b]
> f = ----------------------------------
> Exp[c] - Exp[d]
>
>where a is "other stuff" and b, c and d are simple sums like b = b1 + b2
>+ b3. By default Mathematica seems to shuffle the elements of b, c and
>d in these results such that there will be only positive signs in the
>exponents b, c and d.
>
>I want to force Mathematica to display each of these expressions in the
>form
>
> a Exp[b - c]
> -------------------------------------------
> 1 - Exp[d - c]
>
[snip]
>I've been trying Inputs like
>
> (Exp[-c] Numerator[f]) / (Exp[-c] Denominator[f])
>
>and not getting anywhere.
>
>Ideas?
How about
Simplify[Numerator[f] Exp[-c]]/Simplify[Denominator[f] Exp[-c]]
?
It can be streamlined in a simple procedure, like this:
myCollect[fac_][f_] :=
Simplify[Numerator[f] fac]/Simplify[Denominator[f] fac]
So that it can be called like this:
f // myCollect[Exp[-c]]
A further step would be the identification of the positive signed
exponential in the denominator.
cheers,
Peltio